Timing matters: investigating the interplay of presentation duration and congruency in approximate number processing

The approximate number system (ANS) is an innate number sense ability; it plays a pivotal role in the development of symbolic number ability. Despite studies using a wide range of presentation durations of stimuli to investigate the approximate number processing, limited literature has systematically explored its impact on approximate number processing. Further, if increasing presentation duration leads to improved accuracy, it remains unclear whether this improvement will be driven by better performance in both congruent and incongruent conditions or only in one condition. Addressing these gaps, the present study investigated the impact of presentation duration on the approximate number processing among 45 college-going adult participants from India. The dot number comparison task was used to measure ANS, with stimuli presentation duration manipulated at the following durations: 100, 200, 500, 1000, and 3000 milliseconds (or until response). Based on the congruency of non-numerical features of dots with numerosity of dots, trials were categorized into congruent and incongruent trials. Repeated measure ANOVA revealed a positive relationship between the presentation duration and dot number comparison accuracy. However, a saturation point in performance was observed at a presentation duration of 500 milliseconds, beyond which increased duration did not lead to enhanced accuracy. Further analysis based on congruency revealed that performance improvement was confined only to congruent conditions. Drawing on samples from India, the study offers valuable insights into the ANS.